diff --git a/.changeset/wicked-waves-cheer.md b/.changeset/wicked-waves-cheer.md
new file mode 100644
index 0000000000..1db1bcabc6
--- /dev/null
+++ b/.changeset/wicked-waves-cheer.md
@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+**Account Abstraction:** Fixed User Operation fee estimation when a Bundler Client contains custom `estimateFeesPerGas` hook.
diff --git a/src/account-abstraction/actions/bundler/prepareUserOperation.ts b/src/account-abstraction/actions/bundler/prepareUserOperation.ts
index 9e66c99357..1e27ce957f 100644
--- a/src/account-abstraction/actions/bundler/prepareUserOperation.ts
+++ b/src/account-abstraction/actions/bundler/prepareUserOperation.ts
@@ -409,7 +409,7 @@ export async function prepareUserOperation<
           bundlerClient,
           userOperation: request as UserOperation,
         })
-        request = {
+        return {
           ...request,
           ...fees,
         }